The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 23, 1994
Filed:
May. 11, 1989
Hiroshi Gotoh, Kawasaki, JP;
Isamu Shibata, Fuchu, JP;
Ikuo Maeda, Kawasaki, JP;
Tatsuaki Sakurai, Yokohama, JP;
Ricoh Company, Ltd., , US;
Abstract
A servo method in a multibeam optical pickup in which, at the time of a recording mode, a record information is confirmed and reproduced by a beam for reproduction while the record information is written by a beam for record, and the record information is reproduced by the beam for reproduction at the time of a reproducing mode, comprises the steps of detecting a focus servo signal and a track servo signal with respect to each of the beams for record and reproduction reflected by an optical disk; performing focusing and tracking operations based on the focus servo signal and the track servo signal provided by the beam for record at the time of the recording mode; and performing the focusing and tracking operations based on the focus servo signal and the track servo signal provided by the beam for reproduction at the time of the reproducing mode. In another servo method, the focusing and tracking operations may be performed according to the recording and reproducing modes. An optical pickup comprises a detector for detecting respective track error signals with respect to the preceding and subsequent beams; a tracking control device for performing a tracking servo control by the track error signal detected based on one of the beams; and a tangential control device for performing a tangential servo control by the track error signal detected based on the other of the beams.